1. Field of the Invention
This invention relates to a connection terminal unit of a butt type having a finger-touching prevention structure, which is used, for example, in charging an electric automobile and to a coaxial connector employing the unit.
2. Description of the Related Art
Butt-type terminals--which are connected to each other in face-to-face relation--are advantageous as compared with pin/sleeve type terminals in that a smaller force is required and less abrasion is caused when connecting and disconnecting the terminals. There are, however, various problems to the butt-type terminals especially when used with a high-voltage, high-current passing connector such as a connector for an electric automobile.
FIG. 6 shows an example of a coaxial connector employing a conventional butt-type terminal unit (Japanese Utility Model Application Laid-Open Specification No. 3-48881), in which denoted 51 is a plug connector and 52 a receptacle connector.
The front end surface of a connection terminal 53 of the plug connector 51 is formed as a spherical surface 53a, and the front end surface of a connection terminal 54 of the receptacle connector 52 is formed as a conical recess 54a. In other words, to enlarge the contact surfaces of the terminals in a direction perpendicular to a fitting direction of the connectors 51, 52, the spherical surface 53a and conical recess 54a are employed, which in turn enlarges the opening 56 of a hood 55 of the plug connector 51, resulting in a fear that a finger or the like enters into touching with the connection terminal 53 to cause an electric shock. To avoid this, the hood 55 may be elongated so as to put the connection terminal 55 out of reach. It is, however, not practical since the entire length of the connector becomes elongated.
FIG. 7 shows a connector employing a conventional pin/sleeve-type terminal unit (Japanese Utility Model Application Laid-Open Specification No. 60-145560). More specifically, a connection terminal 57 of a not-shown plug connector has a small-diameter projection 58 axially projecting at the front end, and a screw portion 63 provided on the front end surface of the projection 58. A metallic ring 59 is force-fitted over the small-diameter projection 58, and a conical guide 60 of heat-resistant resin material is threaded over the screw portion 63. The receptacle connector 52' contains a connection terminal 62 which has a sleeve 61 for receipt therein of the pin-like connection terminal 57.
In the connector of FIG. 7, the front end of the sleeve 61 and the conical guide 60 cooperate with each other to guide the insertion of the pin terminal 57. In contrast, in the butt-type terminal unit of FIG. 6, neither of the connection terminals 53, 54 has a guiding operation.
The guide 60 of heat-resistant resin material serves to prevent a finger or the like from touching the connection terminal 57. The guide 60, however, is of a structure which is guided by the open end of the metallic sleeve 61 to be inserted into and pulled out of the sleeve, thereby possibly resulting in deformations of the resin material, the production and biting of shavings which may cause adverse effects on connections, and the falling-off of the guide 60 during the inserting or pulling out of the pin terminal 57.